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    What is Grade 351?

    This is an extremely fine retention filter for critical gravimetric analysis of very fine particles, such as barium and lead sulphates, stannic and nickel sulfide for use in glazes, coatings and pigments. It also filters calcium oxolate, calcium fluoride and cuprous oxide. It eliminates large particles that might otherwise interfere with sensitive instrumentations. Likewise it is highly recommended for the analysis of insoluble particles in oils and animal or vegetable fats. A common example is use of Grade 351 as a calcium carbonate filter for analysis in the cement industry. Grade 351 has the smallest pore size of all our filter paper grades. The ash content is 0.007%. The high purity of Grade 351 filters also makes them suitable for processes that require ashing.

    Whatman Cross Reference = No.42
    Speed class Very Slow Filtering
    Thickness (mm) 0.14
    Pore size (μM) 2-3
    Weight (g/m²) 84
    Filtration Speed (sec*) 180
    Burst Strength (Kg/cm²) > 0.20
    *According to DIN 53137
    Diameter (mm) Product Code
    mm: 55 Product code: 351055
    mm: 70 Product code: 351070
    mm: 90 Product code: 351090
    mm: 110 Product code: 35110
    mm: 125 Product code: 351125
    mm: 150 Product code: 351150
    mm: 185 Product code: 351185
    mm: 240 Product code: 351240
    mm: 300 Product code: 351300
    mm: 320 Product code: 351320